Combined protractor and spirit level



NOV. 29, A JOHNSON COMBINED PROTRACTOR AND SPIRI T LEVEL Filed May 2, 1951 Patented Nov. 29, 1932 UNITED STATES ARTHUR W. JOHNSON, OF LITC'HFIELD, NEBRASKA COMBINED PROTRACTOR AND SPIRIT LEVEL Application filed May 2, 1931. Serial No. 534,620.

with the spirit tube disposed in a plane parallel with. a surface of the straight edge and in this position it may be employed with the straight edge for fixing a body in a horizontal position. By oscillating the protractor body the spirit tube is located at an angle with respect to the adjacent surface of the straight edge the degree of which angle is indicated upon the protractor body at the point thereon which is intersected by the plane of the adjacent surface of the straight edge.

A still further object of the invention is to provide a novel means for securing an oscillatable protractor body in a straight edge.

A still further object of the invention is to provide a novel means for frictionally maintaining the oscillatable protractor body in any set position in the straight edge.

The invention will be best understood from a consideration of the'following detailed description taken in connection with the accompanying drawing forming part of this specification, with the understanding, however, that the invention is not confined to any 0 strict conformity with the showing of the drawing but may be changed or modified so long as such changes or modifications mark no material departure from the'salient features of the invention as expressed in the appended claims.

In the drawing 2 Figure 1 is a view in top plan of the central portion of a straight edge showing the same equipped with the spirit tubes and protractor structure embodying the present in- 1 vention. 1

Figure 2 is a longitudinal sectional view taken substantially on the line 22 of Figurel;

Figure 3 is a View in transverse section taken on the line 3-3 of Figure 2.

Referring now more particularly to the drawing wherein like numeralsof reference designate corresponding parts throughout the several views, the numeral 1 indicates generally the body of the spirit level structure, which will hereinafter be referred to as the straight edge. This body has formed in one edge surface a pocket 2. Countersunk in the surface of the body 1 in which the pocket 2 is formed, is an elongated plate 3 in which is formed an elongated slot 4. The under surface of the plate has depending therefrom the spaced parallel flanges 5 which or opening 4 as illustrated.

Disposed in the slot 4 of the plate is a semicircular protractor body which is indicated generally by the numeral 6. This body has the two spaced walls 7 which are connected about their convex edges by the intermediate portion 8. The outer surfaces of the walls 7 are scaled through 180 of a circle.

Disposed between the walls 7 at a point inwardly of the straight edges thereof, is a partition 9 which forms with the walls a pocket 10 which extends diametrically of the protractor body. l/Vithin this pocket 10 there is positioned upon each side of the diametrical center of the body, a spirit tube 11. At the diametrical center of the body are laterally directed supporting pins or trunnions 12 which position in suitable bearings in the flanges 5 adjacent thereto.

The surface of the plate 3 at each side of the protractor body is cut in or lowered as indicated at 13 so as to bring the surface in the same planeas the zero and 180 marks upon the adjacent scales, these surfaces also being in the same plane asthe axial centers of the trunnions 12 upon which the protractor body or scales oscillate. by

The walls 7 of the protractor body are bulged outwardly slightly as indicated at are elongated upon opposite sides of the slot 14, adjacent the straight edges thereof and frictionally contact with the supporting flanges 5. This frictional contact of the walls 7 with the flanges 5 serves to maintain the protractor body in any position to which it may be oscillated.

The-arcuate wall 8 or'connecting surface between the walls 7 is pressed outwardly slightly adjacent one end to form the straight surface 15 which is substantially at right angles to the plate 3 by which the protractor body is supported. Adjacent this straight surface 15 of the curved wall 8 are spaced guides 16 through, which extends a latch pin 17; The pin 17 carries a right angularly disposed arm 18 which passes out through a slot 19 in the plate 3 and terminates in a button 20 upon the top of the plate. Between the arm 18and an adjacent supporting element 16 is a spring 21 which is compressed when the latch pin is retracted. The forward end of the pin is rounded and seats in an aperture 22 in the surface 15 so as to hold the protractor body in position where the spirit tubes 11 are disposed in a plane parallelwith the adjacent face of the straight edge body. The rear end of the slot 19 which extends longitudinally of the device joins a lateral slot or recess 19 into which the vertical arm 18-may be oscillated when the pin 17 is retracted, to maintain this pin in retracted position.

While there has been shown and described a pair of straight spirit tubes it is of course to be understood that the invention is not to be limited to the use of such tubes for a single tube may be employed if desired or there may be employed in place of the single .tube a curved tube of the type at present in use or a pair of such curved tubes may be substituted for the pair of straight tubes now shown.

F ro'rn the foregoing it will be readily understood that in the use of the present clevice if a body, such for example as a beam in abuilding, is to be disposed at an inclination of 45, the latch pin 17 is retracted to release the protractor body and the body is that one of the tubes will be hidden within the pocket 2 in which the protractor swings while the other will be exposed to full view. The advantage of using two tubes in the place of a single long tube will be readily seen for if a single tube were employed the hair line would be disposed directly across the center of the protractor and some difficulty might be experienced in seeing the same and determining when the bubble is in position therebeneath.

Formed in the plate 3 to extend downwardly from the top thereof to the passages in the bodies 16 in which the pin 17 rides, are oil passages 17, the upper ends of which are enlarged slightly and threaded to receive the screws 18, which closethese passages to prevent the entrance of dirt and dust. These oil passages 17. are provided to make it possible to keep the pin 17 well oiled so that it will reciprocateeasi-ly in its supporting members as it is very essential that the movement of this pin be smooth and easy.

Having thus described my invention, what is claimed is l. The combination with a straight edge having a pocket in one surface thereof, of a body disposed in said pocket comprising a pair of spaced parallel semi-circular plates, one of said plates having a protractor scale along the outer edge of its outer face, pivot pins at the radial centers of said plates oscillatably supporting the same in the pocket, a connecting plate between the first plates parallel with and below the straight edges thereof and forming therewith a spirit tube pocket, a spirit tube in said last pocket, and means for securing the body in an oscillated position, consisting of a bulged-out portion of one of said first plates which maintains resilient frictional contact with an adjacent portion of the structure.

2. The combination with a straight edge having a pocket in one face thereof, of a plate designed to be secured over said pocket and having a pair of depending spaced parallel side walls, said plate having an elongated recess therein, a semi-circular body havinga plate along its straight side which fits into said recess, the body extending through the recess into said pocket, pivotal means connecting the body at its radial center wit-h the adjacent walls of the first mentioned plate, a protractor scale formed along the curved edge of said body on one side face thereof, a spirit tube carried by the said body beneath the plate which forms a part thereof, said last plate having openings therein for viewing said tube, a latch member reciprocably carried by said first plate between the walls thereof, and means for coupling one end of said latch with said body to maintain the body in a desired position.

3. The combination with a straight edge having a pocket in one face thereof, of a face plate covering said pocket and having a pair of spaced parallel walls depending from its under side into the pocket and further having a central opening therein, a semi-circular body disposed in said pocket between said walls and having its straight side lying in said opening, pivot means between the radial center of said body and the adjacent walls of the plate, a protractor scale formed along the curved edge of the body upon one side face, a spirit tube carried by the body and extending parallel with its straight side, a pair of lugs disposed between said walls at one side of the body, a pin member reciprocably carried by said lugs and having one end normally engaging said body to retain the same in a desired position, and a button exposed upon the outer side of said face plate and connected through an aperture in the face plate with said pin whereby shifting of the pin may be effected.

4. The combination with a straight edge having a pocket in one surface thereof, of a protractor body comprising two spaced parallel semi-circular plates each having a scale along the outer edge of its outer face, a connecting body between said plates along the curved edges thereof, a connecting body between the plates spaced inwardly from and parallel with the straight edges thereof, said last named body forming a spirit tube pocket between the plates, a spirit tube disposed in said last pocket, supporting trunnions carried by and projecting from the radial centers of the semi-circular plates for oscillatably supporting the protractor body in the straight edge pocket, and latch means for maintaining the protractor body in fixed position in the straight edge pocket.

5. The combination with a straight edge having a pocket in one surface thereof, of a protractor body comprising two spaced parallel semi-circular plates each having a scale along the outer edge of its outer face, a connecting body between said plates along the curved edges thereof, a connecting body be tween the plates spaced inwardly from and parallel with the straight edges thereof, said last named body forming a spirit tube pocket between the plates, a spirit tube disposed in said last pocket, supporting trunnions carried by and projecting from the radial centers of the semi-circular plates for oscillatably supporting the protractor body in the straight edge pocket, latch means for maintaining the protractor body in fixed position in the straight edge pocket, and frictional means for maintaining the protractor body in any set position in the straight edge pocket.

In testimony whereof I hereunto aflix my signature.

ARTHUR W. JOHNSON. 

